The cutter heads of wood chippers are provided with one or more blades which are detachable so that they may be sharpened and replaced.
As blade resharpening results in the reduction in blade width, compensation for such a change in width is required. Insofar as it is known, such compensation has required, prior to the present invention, either the adjustment of a series of set screws spaced lengthwise of the backing edge of the blade appropriately for contact with the backing surface or the filling of the space then resulting between the backing edge of the blade and the backing surface by means of shims or by molten lead. Some inexpensive machines make no provisions by which wear may be compensated for.
In addition, where a cutter head is provided with only one knife or some other non-symmetrical knife arrangement, the loss in weight of a resharpened blade presents a problem since the balance of the cutter head is lost as the blade is consumed by resharpening. The adjustment of knives to compensate for the results of resharpening in the ways previously referred to require some skill and are time consuming and the use of molten lead is both cumbersome and inconvenient.
Chippers commonly use cutter heads having a symmetrically arranged set of knives to counter loss of balance and it is necessary to keep the knives in sets and to sharpen and adjust them evenly to maintain that balance.